Thermoplastic materials forming orthopedic casts for wrapping limbs and other human body parts have been known and used in the past. A representative material of this type is one known as HEXCELITE and is made and sold by Hexcel Corporation, Dublin, Calif. Such a material is disclosed in U.S. Pat. No. 4,273,115. The material includes a large mesh, flexible fabric carrier, typically a cotton knit material, impregnated with a polyester polymer to provide a relatively thick coating of the polymer on the knit material while retaining substantially large openings in the mesh or fabric of the knit material. The cast material made in this manner is somewhat flexible and is capable of being wound into a roll to form a cylindrical package for storage until it is ready for use.
When the cast material is to be used, it is heated to a temperature above the softening point of the polymer or until the cast material softens to a flexible or pliable condition. Then the cast material can be readily molded or wrapped on the limb or body part of a patient. The softening of the cast material is achieved by immersing it in hot water. Upon being removed from the water, the cast material is wrapped immediately on the limb or body part, and the convolutions of the wrapped cast material bond to each other to form a unitary cast having high strength characteristics yet the cast is lightweight in construction, is abrasive and shock resistant, and is porous to permit air circulation therethrough.
A problem associated with orthopedic cast material of this type is the fact that the convolutions of the material adhere to each other when the cast material is being heat softened in hot water. Separating the convolutions then becomes difficult because the resin, when heated, adheres strongly to anything which it engages.
This problem has been overcome in the past by providing a plastic separator sheet between the convolutions of the cast material. The plastic of the separator sheet is generally unaffected by the hot water. Thus, the convolutions do not engage each other during the heat softening of the cast material. The separator sheet is removed from the cast material during the wrapping of the cast material or a limb or body part. Such a separator sheet is one of the type disclosed in U.S. Pat. No. 4,143,655. A separator sheet of this type is relatively high in cost and is hard to handle when the cast material is being wrapped onto a limb or a body part. Also, the separator sheet has a tendency to retain hot water which drips onto the patient and causes discomfort during the wrapping process.
Because of the aforesaid drawbacks of conventional separator sheets for orthopedic cast material of the type described, a need has arisen for improvements in the means and techniques for keeping adjacent convolutions of a roll of orthopedic cast material separated from each other during immersion of the role in hot water to thereby permit such cast material to be readily heated and then quickly wrapped onto the limb or body part of a patient.